Depending of whether they also think its worth changing the Dual Mass Flywheel as well at the same time.

Do hill starts you're less likely to notice to the slip, as you are manual slipping the clutch yourself. Clutch slip really comes noticeable with it fully engaged and you stomping on the accelerator, or increasing the load on the engine eg, cruising on a flat bit of road in fifth, hitting an incline and keeping it in fifth.